Fix local CI: Dynamic task lists and aarch64 support

build/ci/README.md

@@ -7,6 +7,59 @@ Workflow descriptions are located in `.github/workflows`, platform specific PCP
 * QA: Runs the entire testsuite on pull requests and daily at 17:00 UTC, and publishes the results at https://performancecopilot.github.io/qa-reports/
 * Release: Triggered when a new tag is pushed, creates a new release and pushes it to https://packagecloud.io/performancecopilot/pcp
 
+## Quick Start - Running CI Locally
+
+Test your changes against a single platform:
+```bash
+# Full CI pipeline (setup → build → install → init_qa → qa_sanity)
+build/ci/ci-run.py ubuntu2404-container reproduce --until qa_sanity
+
+# Just setup and build (quick feedback on compilation issues)
+build/ci/ci-run.py ubuntu2404-container reproduce --until build
+
+# Run individual tasks
+build/ci/ci-run.py ubuntu2404-container task build
+build/ci/ci-run.py ubuntu2404-container task qa_sanity
+```
+
+## Supported Platforms for Local Testing
+
+See `.github/workflows/ci.yml` for the authoritative list of platforms being tested in CI. Currently tested platforms include:
+
+- ubuntu1804-i386-container (Ubuntu 18.04, 32-bit)
+- ubuntu2004-container (Ubuntu 20.04)
+- ubuntu2204-container (Ubuntu 22.04)
+- ubuntu2404-container (Ubuntu 24.04 LTS, recommended for new development)
+- fedora42-container (Fedora 42)
+- fedora43-container (Fedora 43)
+- centos-stream8-container (CentOS Stream 8)
+- centos-stream9-container (CentOS Stream 9)
+- centos-stream10-container (CentOS Stream 10)
+
+Additional platforms available in the codebase but not in the default CI matrix (see comments in `.github/workflows/ci.yml`):
+- debian12-container
+- debian13-container
+- fedora-rawhide-container
+
+## Architecture Support
+
+By default, the CI scripts use your native host architecture:
+- **macOS ARM64 (Apple Silicon)**: Runs native ARM64 containers (fast, no emulation)
+- **macOS Intel**: Runs amd64 containers natively
+- **Linux**: Always uses amd64 containers
+
+To force amd64 emulation on macOS for exact CI parity (requires Rosetta):
+```bash
+build/ci/ci-run.py --emulate ubuntu2404-container reproduce
+```
+
+## Troubleshooting (macOS)
+
+If you see "exec: Exec format error" with amd64 emulation, Rosetta may have become unstable. Restart the podman machine:
+```bash
+podman machine stop && podman machine start
+```
+
 ## Reproducing test failures
 ```
 build/ci/ci-run.py ubuntu2004-container|fedora38-container|centos9-container|... reproduce